Audio during calls not working on iphone7 but music is working fine

Hello All,

I have iphone7 with IOS 12.4.1. It was working fine till morning. Suddenly while on a call, the person on the other side couldnt hear. Niether I could hear. I cut the line and tried several calls. Everytime the other person couldnt hear nor could I hear. It cannot be hardware issue as both mic as well as speaker not working. I have tried to do soft reboot as well as hard reboot of the phone many times. I have also gone to setting and reset all settings. It worked for 5 minutes but then again the same problem. When this problem happens, even Siri is not working (as Siri is also not able to hear our voice). Bluetooth is turned off. I tried to put an earphone but that also didnt work.

I can hear music when I play a song or video. But when on a call, speakers do not work. Intermittently I do get calls when I can hear but most of the times its not working.

Let me know if anyone has any idea whats going on. Would really appreciate.

ThankYou.